// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_COMPOSITOR_LAYER_OWNER_H_
#define UI_COMPOSITOR_LAYER_OWNER_H_

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "ui/compositor/compositor_export.h"
#include "ui/compositor/layer.h"

namespace ui {
class LayerOwnerDelegate;

class COMPOSITOR_EXPORT LayerOwner {
public:
    LayerOwner();
    virtual ~LayerOwner();

    void SetLayer(Layer* layer);

    // Releases the owning reference to its layer, and returns it.
    // This is used when you need to animate the presentation of the owner just
    // prior to destroying it. The Owner can be destroyed soon after calling this
    // function, and the caller is then responsible for disposing of the layer
    // once any animation completes. Note that layer() will remain valid until the
    // end of ~LayerOwner().
    scoped_ptr<Layer> AcquireLayer();

    // Asks the owner to recreate the layer, returning the old Layer. NULL is
    // returned if there is no existing layer, or recreate is not supported.
    //
    // This does not recurse. Existing children of the layer are moved to the new
    // layer.
    virtual scoped_ptr<Layer> RecreateLayer();

    ui::Layer* layer() { return layer_; }
    const ui::Layer* layer() const { return layer_; }

    void set_layer_owner_delegate(LayerOwnerDelegate* delegate)
    {
        layer_owner_delegate_ = delegate;
    }

protected:
    void DestroyLayer();

    bool OwnsLayer() const;

private:
    // The LayerOwner owns its layer unless ownership is relinquished via a call
    // to AcquireLayer(). After that moment |layer_| will still be valid but
    // |layer_owner_| will be NULL. The reason for releasing ownership is that
    // the client may wish to animate the layer beyond the lifetime of the owner,
    // e.g. fading it out when it is destroyed.
    scoped_ptr<Layer> layer_owner_;
    Layer* layer_;

    LayerOwnerDelegate* layer_owner_delegate_;

    DISALLOW_COPY_AND_ASSIGN(LayerOwner);
};

} // namespace ui

#endif // UI_COMPOSITOR_LAYER_OWNER_H_
